Enantioselective Isoprenylboration Reaction of Aldehydes Catalyzed by a Chiral Phosphoric Acid

Abstract

The BINOL‐derived chiral phosphoric acid (R)‐TRIP is utilized as an organocatalyst in the asymmetric isoprenylboration reaction of aldehydes, wherein hydrogen‐bond interactions play a key role in the control of enantioselectivity. A wide arrays of enantioenriched dienyl homoallyl alcohols, including two natural products (−)‐Ipsdienol and (−)‐Ipsenol, have been successfully constituted. The synthetic application to chiral isoprenylated isobenzofuranone, vinyloxirane and cyclohexene derivatives has also been disclosed.

An overview of the applications of chiral phosphoric acid organocatalysts in enantioselective additions to CO and CN bonds

“…For example, in 2019 Huang used pinacolyl isoprenylboronate 412 (R 2 , R 3 , R 4 , = H; R 5 , R 6 = CH 2 CH 2 ) as allylating agent, in a mixture of toluene: CCl 4 in presence of ( R )- BPA2 to afford isoprene substituted alcohols 413 in good yields and enantioselectivities (90–98%, 66–97% ee) (Scheme 122a). 328 The scope of this reaction can be applied to a wide array of aromatic, aliphatic and conjugated aldehydes 86 .…”

The Synthesis of Ipsenol and Ipsdienol: A Review (1968–2020)

“…Zhang and co‐workers have exploited the reactivity of “boro‐isoprene synthon” 4,4,5,5‐tetramethyl‐2‐(2‐methylenebut‐3‐en‐1‐yl)‐1,3,2‐dioxaborolane ( 106 ) (Figure 3) [prepared as reported by Erver and Hilt by reacting isoprenylpotassium ( IV ) (Figure 3) with 2‐isopropoxy‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolane], [91] against 3‐methylbutanal, in the presence of the BINOL‐derived chiral phosphoric acid ( R )‐TRIP, to synthesize ( S )‐ipsenol ( I ) (Scheme 38) in 60 % yield and 50.6 % ee [90] …”

“…Zhang has described the reaction of 4,4,5,5‐tetramethyl‐2‐(2‐methylenebut‐3‐en‐1‐yl)‐1,3,2‐dioxaborolane ( 106 ) (Figure 3) with 3‐methylbut‐2‐enal, in the presence of the BINOL‐derived chiral phosphoric acid ( R )‐TRIP, to synthesize ( R )‐(−)‐ipsdienol ( II ) (Scheme 38) in 75 % yield and 85.6 % ee [90] …”

Brønsted Acid‐Catalyzed General Petasis Allylation and Isoprenylation of Unactivated Ketones

“…We also probed the versatility and robustness of this Petasis reaction by using isoprenylboronic ester 3 b , instead of 3 a , to access the corresponding quaternary dienyl amine 4 ab (Table ). Under the standard reaction conditions the expected product 4 ab was formed in 72 % yield (Table , entry 1); this result was slightly improved by conducting the experiment at 50 °C (75 % yield; Table , entry 2).…”